Tree List Lookup

The DevExpress ASP.NET Drop-down Edit (ASPxDropDownEdit) represents an editor containing an edit box to display the editor value (defined via the Text property) and a specific button that opens a drop-down window whose content can be templated (using the DropDownWindowTemplate property). The ASPxDropDownEdit allows you to define its value based on the value of another control (or the values of other controls) integrated into the editor's DropDownWindowTemplate.

In this demo, a DevExpress ASP.NET Tree List (ASPxTreeList) control is placed in the dropdown window template of ASPxDropDownEdit. To change the editor value, select a Tree List node and click the Select button. A specific client API exposed by the ASPxDropDownEdit is used in this demo to assign text and a value to the editor (the SetText and SetKeyValue methods), and hide the editor's dropdown window (the HideDropDown method).

Set the DataCacheMode property to `Disabled` to prevent data caching in the Tree List. Otherwise, calling the GetVisibleNodes method in the CustomJSProperties event handler can cause an error. This occurs because the GetVisibleNodes method causes data binding to get nodes that are missing from the cache, but the CustomJSProperties event fires after the control hierarchy is built and the data binding operation fails.